This invention relates to fuel air injector and more particularly to a fuel air injector for an internal combustion engine.
One common type of fuel injector for an internal combustion engine and, in fact, one of the earliest type of injectors used with such engines, comprises a housing that a defines a chamber into which fuel is injected. This chamber communicates with the combustion chamber of the engine through a nozzle port and an injector valve controls the communication of the chamber through this nozzle port with the combustion chamber.
This type of fuel injector has certain advantages in conjunction with two cycle engines although it can be applied equally as well with four cycle engines. However, there is a disadvantage with this type of fuel injector in that the control of the amount of fuel discharged can be somewhat difficult and may be depend on variations in the running condition. One reason for this is that the fuel is injected into a chamber which communicates with the combustion chamber through a valve having a valve member and a valve seat. The clearances between the valve member and valve seat when in their open position can vary due to a number of factors and also the pressure in the combustion chamber may vary. That is, if fuel is injected at any time when the injector valve is opened, than the pressure variations in the pressure in the combustion chamber and variations in pressure within the chamber of the fuel injector due to differences in the distance between the valve seat and valve member can cause variations in the amount of fuel injected. This problem can be particularly acute at times when the compression ratio is high, and the injector valve is opened and fuel is being injected by the fuel injector.
It is, therefore, a principal object of this invention to provide an air fuel injector having a construction which will insure that the amount of fuel injected will not be dependent upon the pressure in the chamber into which the fuel injector discharges or clearances between the valve member and valve seat.
It is a further object of this invention to provide an improved air fuel injector in which the amount of fuel injected will be independent of variations in pressure and differences in clearance between the valve member and the valve seat of the injector valve.
This invention is adapted to be embodied in an air fuel injector for injecting fuel and air into a high pressure area of an internal combustion engine. The injector comprises a housing that defines a chamber and a nozzle port for communicating the chamber with the high pressure area of the engine. An injector valve is provided for opening and closing the communication of the chamber with the high pressure area. A fuel injector injects fuel into the chamber. Means are provided for restricting the communication of the area between the injector valve and the nozzle port with the area of the chamber to which fuel is injected by the fuel injector at least when the injection valve is opened.